Time-limit relay.



E. H. JACOBSi TIME LIMIT RELAY. APPLICATION FILED Aue.22. 1914.

PatenteQ Sept. 18, 1917.

Inventor:

Witnesses:

5 H IS Attornqg.

1 UNITED STATES PATENT OFFICE.

. ERNEST I-I. JACOBS, OF SCI-IENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

TIME-LIMIT RELAY.

Specification of Letters Patent. Patented Sept. 18, 191 *7 Application filed August 22, 1914. Serial No. 858,003.

To all whom it may concern:

Be it known that I, ERNEST H. James, a

citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Time-Limit Relays, of which the following is a specification. I

My invention relates to protective devices for electric circuits, and more particularly to time limit relays and similar protective devices which respond to overload or similar abnormal conditions on the circuit.

It is customary in protecting electric circuits to use protective devices, such as relays, which do not respond instantly upon the occurrence of an abnormal condition on the circuit, such as an overload, but do respond if the abnormal condition persists long enough to be dangerous. In some cases these devices are of the definite time limit type and act only if the abnormal condition persists' for a certain definite length of time, while in other cases the devices are of the inverse time limit type, and the more abnormal the condition on the circuit the quicker the device will operate. The devices should always operate in the same length of time under the same conditions, but many of the devices heretofore used respond more quickly than they should under very abnormal conditions, or else their time interval changes with the lapse of time. Such changes and variations are particularly objectionable where a number of devices are connected to the same circuit and are set to respond to an overload or other abnormal condition in definite sequence. If each relay does not always operate as it should, or if it changes its time setting, the relays will sooner or later operate in a different sequence than that for which they were set.

The object of my invention is to provide time limit device which is simple and accurate and will always operate in the same way under the same conditions. Another object is to provide a time limit device which has many of the advantages of the definite time limit relay and also of an inverse time limit relay. A further object is to provide a time limit device in which the time characteristic and consequently the sequence of operation of the devices can be adjusted very easily and very accurately. Still another object is to improve in general the construction of time limit devices suitable for use on electric circuits.

In carrying out my innvention I provide a time limit mechanism which Will always operate at a definite and uniform rate regardless of conditions on the circuit, and which is set into operation by abnormal conditions on the circuit. I may also provide an electroresponsive tripping device which is energized to an extent dependent upon the condition of the circuit and is normally unresponsive even to abnormal conditions, but which is gradually rendered more and more responsive by the time limit mechanism until finally the electroresponsive device operates to open the circuit or bring about any other change which may be necessary to protect it. The time required for the electroresponsive device to act after the time limit mechanism begins to render the device more responsive is inversely dependent on the extent of overload or other abnormal condition. If the abnormal condition, as, for example, an

overload, is very slight, the electroresponsive device does not operate until the time limit mechanism has practically completed its travel, while if the overload is very severe the electroresponsive device is able to open the circuit almost as soon as the time limit mechanism begins to act. I also, in accordance with my invention, provide suitable means for permitting the time limit mechanism to run for a definite period after it is set in operation before'it' begins to affect the electroresponsive device. In this way I se cure a time limit device which is first a definite time limit device, and then, after a definite period has elapsed, becomes an inverse time limit relay. As a result, the relays may be set with difierent definite time intervals, so that when a number of relays connected to the same circuit start simultaneously in response to an abnormal condition, such as an overload on that circuit they will begin to act as inverse time limit relays at different intervals after the appearance of the overload and will always trip out in a definite and predetermined sequence, regardless of the severity of the overload.

My invention will best be understood in connection with the accompanying drawing,

in which merely for purposes of illustration I have shown one of the many various forms in which my invention may be embodied and in which Figure 1 is a side view partly in section of one form of relay embodying my invention with the parts in the normal or inoperative position; Fig. 2 is a diagrammatic view showing the electrical connections and parts of the mechanism of the relay shown in Fig. 1; Fig. 3 is a view of certain parts of the mechanism of the relay shown in Fig. 1 in the position assumed by those parts when the relay is in operation; and Fig. 4 is a view partl in longitudinal section of a clutch forming part of the relay.

In the particular arrangement shown in the drawing, and as best shown in Fig. 2, the main circuit to be protected is controlled by a circuit breaker or oil switch 1 provided with a trip coil 2 which may be energized from any suitable source of current, such as a local circuit 3. The trip coil 2 may be energized in various ways by a time limit protective device, as is obvious to those skilled in the art, and merely for illustration I have shown the trip coil circuit provided with contacts 4; which may be bridged by a bridging contact 5 connected to the time limit relay.

In accordance with my invention I control the trip coil 2 by electroresponsive tripping means energized to an extent dependent on conditions on the main circuit through the oil switch 1. The particular electroresponsive means shown comprises an exciting winding 6 energized by current derived from the main circuit in any suitable manner, as, for example, by a current transformer 7 if the device is to respond to overload. If the device is to respond to other abnormal conditions the connections to the winding (5 will be made in such manner that the excitation of the winding is dependent upon the extent of said other abnormal conditions. I prefer to make the winding 6 in the form of a solenoid or coil, which may have a stationary core 8, and also has a freely movable armature 9, preferably made in'the form of a plunger and suitably mounted so as to be able to respond to the excitation of the windin 6 and thereby energizethe trip coil 2. in the particular device shown in the drawing the plunger or armature 9 is loosely mounted on a rod 10 extending longitudinally of the winding 6, and connected at its upper end to the bridging contact 5. The armature 9 lifts the rod 10 and contact 5 by means of a sleeve 10 secured to the rod 10 and carried up by the armature into a recess in the core 8. The armature 9 is normally at such a distance from the winding 6 that it is not attracted by the winding into position to actuate the bridge member 5 and thereby bridge the trip coil 2, even though the overload upon the circuit to be protected is severe.

The winding 6 and armature 9 form in effect an instantaneous electroresponsive tripping relay normally so set as to be unaflected by severe overloads on the main circuit. In order to render the armature 9 responsive to the winding 6 and secure an inverse time limit effect, I provide suitable mechanism which operates when an overload, for example, appears on the main circuit and gradually and inefl'e t changes the etting of the relay at a definite and uniform rate independent of the severity of the overload to render the relay more and more responsive, as for example, by gradually reducing the distance between the winding 6 and the armature 9. This gradual increase in responsiveness of the armature to the winding may be brought about in various ways, but the preferred construction is that shown in the drawing, in which the armature 9 rests upon a spacer or elongated washer 11, which in turn rests upon a movable foot 12. A suitable guide, such as a rod 13, is provided for the foot 12 which is moved vertically upward by some suitable means, such as a time limit mechanism, to gradually raise the armature 9 until eventually the attraction of the winding 6 is su'tlicient to instantaneously raise the freely movable armature 9 into operative position and actuate the bridging contact 5, thereby energizing the trip coil 2. If the overload is very slight, the excitation of the wind ng 6 will e orrespondingly slight, and the armature 9 will not be actuated by the winding until the armature reaches almost the upper limit of its movement, but if the overload is very severe the winding will be strongly excited and will lift the ma ur 9 to ripp Pwition almost as soon as the foot 12 moves.

In order to prevent premature operation of the armature 9 under very severe overead I may 0 pr po on t e parts that the armature is normally outside the effective magnetic field of the winding 6 and is entirely unresponsive to the winding until after he time limit mechanism controlling the foot has been set in operation. I may also positively restrain the armature, as, for example, by an armature lock 14, which normally prevents movement of the armature 9, but is thrown out of the way when the time limit mechanism egins to operate by some suitable means, such as a project on 15 so positioned that it is engaged by the foot 12. 1 7

The gradual and steady movement of the armature 9 toward the winding 6 by the time limit mechanism causes a gradual decrease in the air gap between the winding and the armature and a gradual increase in the ment is automatically brought about by some suitable mechanism which responds when an overload or any other abnormal condition to which the relay responds appears upon the main circuit. In such a device as that shown in the drawing I prefer to set the mechanism in operation. by some means which will instantly respond when an overload or other abnormal condition appears. I may, for example, use an overload relay 16 connected to the current transformer 7 and provided with calibrating or adjusting means, such as an adjustable stop 17, the position of which may be varied at will so as to vary the position of the plunger of the relay andconsequently the amount of overload required to operate the relay. This overload relay is providedd with cooperating contacts 18 and 19 brought into engagement when an overload appears on the main circuit, whereupon the time limit mechanism is set into operation and, the foot 12 begins to rise at a definite and constant rate,,lifting the armature 9 until presently it is attracted by the winding 6, whereupon the trip coil 2 is energized and the switch 1 opens.

' The particular form of time limit mechanism which I have illustrated comprises a motor mechanism having an actuating windiug, such asthe coil 20, energized when the relay contacts 18 and 19' are brought into operative relation, and provided with an armature, such as the plunger 21, which sets in operation the time limit mechanism when the winding 20 is energized and thereby gradually raises the step 12. The actuating winding 20 can be energized from the local circuit, as shown, or from any other suitable source such as current derived from the main circuit, or the overload relay 16 may be omitted and the actuating winding 20 energized directly by current derived from the main circuit, the parts being so proportioned that the plunger 21 moves only when there is an overload on the main circuit. The relative position of the actuating winding 20' and the plunger 21 when in its lowest position can be varied at will by the adjustable I tubular guide and stop 22, which is threaded and may be raised or lowered at will to vary the travel of the plunger and also vary its initial position.

When the armature of the motor mechanism moves the mechanism for gradually moving the parts toward operative position is set in motion. The motor mechanism may drive the actuating mechanism directly if desired, but in the preferred construction energy is stored in a suitable driving device, such as a coiled spring, which then drives the actuating mechanism with a substantially uniform torque. In the preferred construction, as best shown in Fig. 2, the armature 21 of the motor mechanism is connected to mechanism comprising a rotatable driving member 23 connected to one end of a coiled driving spring 24, the other end of which is connected to a rotatable retarded actuating member 25 preferably mounted coaXially with the driving member 23 shaft 26 to which the actuating member 25 is fixed, and on which the driving member 23 is loosely mounted. When the motor mechanism is energized the driving member 23 is rotated about the shaft 26 and winds up the driving spring 24:, the energized motor mechanism holding the driving member 23 stationary with the spring wound up. The driving spring has suilicient torque to drive the shaft 26 and actuating member 25 in a counterclockwise direction and thereby bring the parts of the device into position to trip the switch 1 and open the main circuit. The actuating member is compelled to move ata definite and uniform rate by some suitable retarding means, one form of which is hereinafter more fully, described.

Tn order to maintain a substantially uniform torque upon the actuating member the drivin spring 2 1 is comparatively long and is always under considerable tension. it is preferably made in the form of a spiral spring like a clock spring and unwinds to only a slight extent in driving the actuating member In order to prevent the driving spring 2 1 unwinding more than desired suitable stops are provided, such as a pin 27 on the driving member 25 mounted in position to cooperate with a stop 28 on the driving member 23. hen the driving member 23 is rotated by the motor mechanism the stop 28 moves away from the pin 27 as the spring 2-1- is wound up, after which the partial unwinding of the spring causes the pin 27 to overtake the stop 28, whereupon further relative movement of the drivingmem ber 23 and actuating member 25 is prevented.

The definite and uniform movement of the actuating member 25 maybe transmitted to the armature 9 in various ways. In the preferred construction shown in the drawings I providev a circuit controlling lever 29 having one end pivotally connected with the movable foot 12 and operatively related at an intermediate point 30 to the actuating -member 25. The other end 31 of the lever 29 projects beyond the actuating member 25 and is preferably provided with a pin or roller. The ,foot 12 can not be moved by the actuating member 26 unless in some way the projecting end of the lever 29 is restrained so that the lever can tilt about its projecting end as a fulcrum and thereby cause the other end to move and lift the foot 12, since as long as the end 31 is unrestrained the lever 29 is merely a link pi voted to the foot 12 and to the actuating member 26, and the upward movement of the actuating member is idle so far as moving the armature 9 is concerned. In order to cause this tilting of the circuit controlling lever 29 I provide a stop 32 preferably mounted on the framework of the device, and nor mally stationary in such a position that it is engaged by the pin or roller on the projecting end 31 of the lever, whereupon, as best shown in Fig. 3, the lever 29 becomes a lever of the third class, with the armature 9 as the load, the actuating member 25 as the power, and the stop 32 as the fulcrum, so that further movement of the actuating member 25 tilts the lever and raises the armature 9 until it is in operative relation to the winding 6.

It is often desirable that a certain time interval elapse between the energizing of the motor mechanism and the beginning of the movement of the armature 9. By making this interval different on each relay connected to the circuit the relays can be made to operate in a definite sequence. To secure this definite time interval I permit the actuating member 25 to move idly for a period of time at a definite and uniform rate, and while it is moving idly in a counterclockwise direction the relay is a definite time limit relay. This idle movement of the actuating member may be secured by various forms of lost motion connection between the actuating member and the armature 9, but is preferably formed by positioning the stop 32 so that it is at a distance from the projecting end 31 of the lever 29 when the lever is in normal inoperative position, as shown in Fig. 1. To vary the time interval I provide suitable means such as an adjusting screw 33 by means of which the stop 32 can be moved up and down to vary the distance between it and the initial position of the end 31 of the lever. WVhen the relay is energized the actuating member 25 begins to move and the lever 29 is carried along idly until its projecting end 31 engages the stop 32, whereupon further movement of the actuating member 25 lifts the other end of the lever and the armature 9 at a definite and uniform rate until finally the armature 9 is picked up by the winding 6.

The device may be made a definite time i limit relay by omitting the elect-roresponsive winding 6 and armature 9 and connecting the circuit controlling lever 29 directlyrto the rod or to the contact 5 for energizing the trip coil 2. In this case the time limit mechanism completes its travel and energizes the trip coil 2 in a definite period of time, regardless of how severe the overload on the main circuit may be. This period is the time required to carry the end 31 of the lever 29 into engagement with the stop 32, plus the time required for the other end of the lever to-move the contact 5 into engagement with the contacts 4 of the trip coil circuit.

In order to control the rate of movement of the actuating member 26 I provide some suitable retarding means, preferably a train of gearing 34 connected to said member and controlled by an escapement, which may be provided with an adjustable regulating weight 35. This type of retarding mechanism causes the actuating member to move at a constant rate regardless of the extent of overload and consequently the relay operates with a high degree of precision.

In some cases the overload may not persist long enough to cause the time limit device to open the circuit breaker 1. In such cases it is desirable that when the relay is again energized it will have the same time lag as before. In order to secure this result I provide means by which when the motor mechanism 21 is deenergized the driving member 23 and actuating member are freed from the retarding mechanism and can return to initial position instantly. I provide a clutch mechanism between the actuating member 25 and the retarding device, the particular clutch shown comprising a hub 36 mounted on a shaft geared to the actuating member 25. Around this hub is wrapped a closely fitting flexible connector 37 having one end connected to a driving gear 38. When the gearing is being driven by the driving spring 24 the wheels turn in the proper direction to cause the flexible connection 37 to wind up and thereby grip the hub 36. Upon a slight reversal of the gearing the flexible connector 37 is loosed from the hub and thereupon the parts drop back into initial position instantly and are ready for the next operation. To assist in stopping the parts in their initial position, I provide a fixed lug or stop 39 in the path of movement of a lug 40 on the driving gear 38.

My invention may be embodied in many other forms than that shown and described, and I therefore do not wish to limit myself to the precise arrangement disclosed except in so far as it is limited by the scope of the appended claims.

hat I claim as new and desire to secure by Letters Patent of the United States, is:

1. A protective device for electric circuits comprising a winding energized by current derived from the circuit to be protected, a freely movable circuit controlling armature normally separated from said winding and unaffected thereby, and a definite time limit mechanism rendered operative in response to abnormal conditions on the circuit to reduce the distance between said winding and said armature at a definite rate which is independent of conditions on said circuit.

2. A protective device for electric circuits comprising a winding energized to an extent dependent upon conditions in the circuit to be protected, a circuit controlling armature normally separated from said winding by an air gap which renders said armature unresponsive to abnormal conditions in said circuit, of definite time limit mechanism operative in response to abnormal conditions on said circuit to progressively vary the setting of said relay to increase its sensitiveness at a definite and uniform rate which is independent of abnormal conditions.

I. A protective device for electric circuits, comprising awinding'energized by current derived from the circuit to be protected, a circuit controlling armature responsive to said winding but normally prevented from responding and moving into operative position, and a time limit actuating mechanism for increasing the responsiveness of said armature at a definite and constant rate which is independent of conditions on said circuit.

5. A protective device for electric circuits comprising a windingenergized to an extent dependent upon conditions in the circuit to be protected, a tripping armature actuated by said winding but normally unresponsive thereto, a time limit mechanism operative at a definite and uniform rate, means responsive to predetermined abnormal conditions on said circuit for setting said mechanism into operation, and connections whereby said mechanism moves said armature a definite time after said mechanism is set in operation and at a definite rate independent of conditions on said circuit to increase the responsiveness of said armature to said winding.

6. A protective device for electric circuits comprising a winding energized to an ex tent dependent upon conditions in the circuit to be protected, a tripping armature for said winding normally unresponsive thereto, a time limit mechanism operative in response to abnormal conditions on said circuit at a definite and uniform rate which is independent of said abnormal conditions, and a lost motion actuating connection between said mechanism and said armature which permits said mechanism to move independently of said armature for a definite interval of time and then enables it to move said ar mature toward said winding.

7. A protective device for electric circuits comprising a winding energized to an extent dependent upon conditions in the circuit to be protected, a tripping armature for said winding normally unresponsive thereto, a time limit mechanism responsive to abnormal conditions on said circuit and constructed to operate at a definite and uniform rate which is independent of said abnormal condition, connections whereby said mechanism moves said armature toward said winding at a definite rate, and adjusting means for varying at will the time interval between the response of said mechanism to abnormal conditions and the movement of said armature.

8. In a protective device for electric circuits, the combination of time limit actuating mechanism comprising a movable actuating member, a normally stationary stop mounted adjacent the pathof said member, a circuit controlling lever pivoted on said actuating member in position to be carried by said member into contact with said stop and thereby actuated by further movement of said member, and means for at will vary ing the distance between said stop and the initial position of said lever.

9. A protective device for electric circuits comprising a circuit controlling member, a control lever in operative relation at one point with said member, a time limit actuating mechanism pivotally connected to said lever at another point to move it, and a stationary adjustable abutment mounted in the path of said lever to engage it at a third point whereby further movement of said time limit actuating mechanism tilts said lever about said abutment as a fulcrum and actuates said circuit controlling member.

10. A protective device for electric circuits comprising a movable retarded actuating member, circuit controlling means comprising a control lever movably mounted on said actuating member and normally. in inoperative position with one end projecting, a normally stationary abutment mounted adjacent said actuating member, and motor mechanism responsive to abnormal conditions on said circuit for moving said actuating member to bring the projecting end of said control lever into engagement with said abutment and to con tinue said movement until said abutment forces said control lever into operative position.

11. In a time limit device for controlling electric circuits, the combination of a motor mechanism responsive to abnormal circuit conditions and comprising a retarded member movable at a definite and uniform rate, a control lever pivoted on said retarded movable member and normally in inoperative position, and a stationary stop mounted adjacent said member in position to be engaged by said lever at a predetermined point in its travel and to cause said memher by its further movement to move said lever about its pivot into operative position.,

12. A time limit device for electric circuits comprising a retarded actuating member, motor mechanism responsive to abnormal circuit conditions for driving said member, a circuit controlling lever pivoted on said member, and an adjustable stationary stop mounted in the path, of said lever in such a position that said actuating member by its movement carries said lever into engagement with said stop and, by its further movement tilts said lever about said stop as a pivot, said stop being adjustable to, vary at will the distance said member must travel from its initial position to bring said lever into contactwith said stop.

13. A time limit relay comprising a motor mechanism responsive to abnormal circuit conditions, energy storing means in which energy is stored bysaid motor a 110-. tarded movable member driven by said energy storing means at a definite and niform rate, normally inoperative circuit controlling means comprising a lever pivoted on: said movable memben, and a stationary stopv mounted adjacent said member tov engage said lever at a, predetermined point in, ts traveland cause said lever to be moved about its pivot byfurther movement of said member and thereby render said circuit controlling means operative.

141. A time limit device for electric circuits comprising a circuit, controlling member, a lever-cooperating, at one end with said member, a motor mechanis responsive to abnormal circuit conditions and com rising a retarded actuating member w 'h engages said lever at an intermediate point,

nd a stationary abutment mounted in the path of movement of the otherend of said lever in position to permit said other end to move without; restraint a definite distance from normal position and to act as a fulcrum for said lever when said other end of said lever is carried into Contact with said abutment by said actuating member.

15. A time limit device for electric circuits comprising; a, circuit controlling memher, a lever cooperating atone end with said member, a stationary abutment for restraining movement of the other end of said lever and acting as a fulcrum for said lever, and motor mechanism responsive to abnormal circuit conditions and comprising a retarded actuating member which engages said lever at a point intermediate its ends and tilts said lever about said abutment as a fulcrum to actuate said circuit controlling member, and means for at will varying the position of said abutment to permit said member to have an idle movement of predctermined extent before tilting said lever about said abutment as a fulcrum.

16. A time limit device comprising a. winding energized in response to conditlons on the-circuit to be protected, a. freel movable armature for said winding, coking means for positively restraining said armature, time limit actuating mechanism, for first rendering said locking means inoperative and then positively moving said armature toward said winding at a definite and uniform rate until said winding moves said armature, and means responsive to conditions on the circuit to be protected for setting saidtime limit mechanism into operation.

17. A time limit device for controlling electric circuits comprising a rotatable drivmg arm, motor mechanism responsive to,

abnormal conditions on the circuit to be protected for moving said arm an. actuat:

ing member mounted adjacent said drivills.

arm to rotate about the same axis, a coi drivingfspring havinn one end connected to.

said driving arm and the other end to said,

member, retarding means for controlling the rate of movement of said actuati member, circuit controlling means actuate I by said actuating memben, and clutch mech anism between said actuating member and said retarding means for restraining movement of said member in one direction and permitting free movement of said memberin the other direction.

In witness whereof, I have hereunto set.

Witnesses:

BENJAMIN B. HULL, HELEN Onrono.

Cople: 01' this patent may be obtained for five cents each, by addressing the Commissioner at Patents. Washington, D. 0. 

